Coating machine



May 14,1946. J. A. PAASCHE COATING MACHINE 4 Sheets-Sheet 1 Filed June 10, 1944 y 946. J. A. PAASCHE 2,400,315

COATING MACHINE Filed June 10, 1944 4 Sheets-Sheet 2 6 .-%/Zz mazfW/jgg May 14, 1946. J. A. PAASCHE COATING MACHINE Filed June 10, 1944 4 Sheets-Sheet 3 W Wm 5 .May 14, 1946. J. A. PAASCHE COATING MACHINE 4 Sheets-Sheet 4 Filed June 10. 1944 g0 INVENTOR. z Jew flfaaxfie l 03 Patented May 14, 1946' UNITED STATES mreiur err-ice 2,400,315 COATING MACHINE Jens A. Paasche, Chicago, Ill.

Application June 10, 1944, Serial No. 539,682

' 12 Claims. (Cl. 91-45) The present invention relates to coating machines, and more particularly to a continuously spraying machine for coating articles with heated material such as wax, paraffin or a thermoplastic substance.

In the manufacture of certain articles it is desired to apply protective coating thereto, particularly where such articles are subject to the effects of humidity, In order to completely coatarticles witha material such as wax, paramn, or some thermoplastic substance, with a minimum of effort and a maximum insurance of a uniform coating, it is desirable to utilize a continuous coating apparatus. In providing a continuous coating apparatusnumerous factors must be considered in order to provide an even smooth moisture resistant coating. In spraying objects in a closed chamber having air spray guns therein, it is necessary to provide for the removal of air and vaporized particles of the coating material which may pass through the inlet and outlet to the apparatus and come in contact with the articles to be coated at a time when the articles the particles are not at the proper temperature. Such particles resting upon the articles will cause the coating to be rough and not closely adherent to the article. Since the chamber in which the spraying takes place has certain vaporized particles therein which do not reach the articles to be coated but may strike the walls of the chamber, it is necessary to provide for means to prevent condensated particles from running down the walls and dripping upon the so that every point on the article may be completely coated with the protective material. In accordance with the present invention there is provided an improved machine for applying a thermoplastic protective coating to the articles I passing therethrough, and which makes provi' sions for the various factors heretofore mentioned and which obviates said disadvantages encountered in machines not having the features incorporated in the present invention.

It therefore is an object of the present invention to provide an improved machine for completely coating articles with a protective material,

It is another object of the present invention to provide an improved coating machine for applying heated material to articles which machine has a minimum of temperature gradients therein.

Still another object of the present invention is to provide an improved spray coating machine the operation of which may be started and stopped without necessitating the disassembly at certain parts thereof.

Other and further objects subsequently become apparent by referehce to the followin description taken in connection with the accompanying drawings wherein Figure l is a perspective view of a coating ma chine embodying the present invention;

Figure 2 is a cross sectional view in the direction of the arrows along the line 2-2 of Figure 1;

Figure 3 is a cross sectional view of the machine as seen in the direction of the arrows along the line 3-3 of Figure 2;

Figure 4 is a perspective view of the lower portion of the inner chamber of the machine;

Figure 5 is a cross sectional view as seen in the direction of the arrows along the line 5-5 01' Figure 3; and

Figure 6 is a detailed view of one element of the machine. i

Referring more particularly to Figure 1, 2, and 3 of the drawings it will be seen that there is shown a machine having an insulated cabinet ll having a top l2, 2. bottom l3, and four walls l5, I6, 61, and I8. The front wall 15 preferably is provided with an opening l9 which is closed by a door 2| which has two panes of wire glass spaced apart to form an insulating air chamber therebetween. The top, bottom, and

walls of the cabinet II are preferably of the double walled type having a heat insulating ma.- terial packed there between. Within the cabinet II there is mounted an inner chamber 22 supported in spaced apart relation with respect to the inner surface of the cabinet H. The inner chamber 22 has rear and front walls 23 and 24 which join side walls 21 and 28. The side walls 21 and 28 extend between the frontwall i5, and the back wall ll of the heat insulated cabinet ll thereby to support the chamber "22 in position. The top of the inner chamber 22 is formed of two members 25 and 26 so that the top constltutes a roof having suflicient pitch so that any vaporized or atomized particles of thermoplastic material coming in contact therewith may condense or agglomerate and rundown the roof to the side walls thereby to prevent the opening 8| in the outer wall I8.

Irina-- formation of drops which might become heavy enough to drop on the articles supported on a conveyor in the center of thechamber. The upper portions of the two side walls 21 and 28 are spaced apart from the upper side walls I8 and I8 of the outer cabinet II. The lower portion of the side wall 28 is also spaced from the side wall I8, but the lower portion of the side wall 21 is mounted adjacent the lower portion of the outer wall I8. The side wall28 is provided with an inlet opening 28 for cooperation with an inlet The inlet in the outer wall I8 is considerably larger than the inlet 28 to the inner wall 28, and the open ing 2I is provided with a hinged hood 82 so that access may be had to the conveyor and.

to a portion of the inner chamber wall 28. The

' opposite wall 21 of the inner chamber is provided with an outlet opening 88, and the outer wall I8 is provided with an outlet opening 34 which is provided with a hinged hood 88. The front wall of the inner chamber 22 is provided with a framed opening 88 which extends to the door opening I8 of the front wall I of the outer cabinet II.. The bottom of the inner material to be applied to the articles which are to receive a protective coating.

By referring to-Flgures 4 and 5 it will be seen that the side walls 21 and-28 which extend bethe outer cabinet II form vertical ducts between the walls of the cabinet and the front and back walls of the inner chamber 22. One duct 42 therefore is formed by a portion of the wall 21 and the front wall 24 of the inner chamber 22 together with'the front wall I5 of the outer cabinet and the flange of the opening 88 at the front of the wall 24 of the inner chamber. An-

. other duct 48 is formed by a portion of the front wall I5 of the outer chamber, the flange 88 adjacent the opening in the front wall 24 of the inner chamber and portions of the front wall 24 and the side wall 28 of the inner chamber 22. Another duct 44 is formed by the back wall 23 and portions of the side walls 21 and 28 of the inner chamber .22 together with the back wall I1 01' the outer cabinet II. These ducts communicate with the spacebetw'een the bottom I8 of the outer cabinet II and the lower portions of the side walls of the inner chamber 22 and the outer cabinet II. At their upper extremities the ducts 42 to 44 communicate with chambers 45 and formed by a plate 41 which extends between the side walls 21 and 28 of the' inner chamber 22 and the walls I5 and I1 of the outer cabinet II. The chamber 45 is connected by a conduit 48 extending upwardly through the top I2 of the insulated cabinet II to a blower 48. The blower 48 is connected to a con 'duit 5|. extending through the top of the cab- The upper plate 41 seen in Figure 3 isspaced from the top l2 of the outer cabinet II so as to form an air duct or conduit 58 which is in communication with a conduit 54 formed between the side wall I8 ofthe outer cabinet and the side wall .21 of the inner chamber, and the conduit 55 formed between the side wall I8 of the outer cabinet II and the side wall 28 of the inner chamber 22. Mounted centrally on the top I2 is an exhaust pipe or conduit 58 having mounted therein a fan 58 driven by a motor 58. The exhaust fan 58 serves to withdraw air from within the chamber 22 and from beneath the hoods 32 and 85 on the inlet and outlet up through the conduits 55 and 54 to the exhaust pipe 86. The suction produced by the exhaust fan 58 is sufficient to prevent vapor particles ofheated coating material from dropping downwardly on the ar ticles supported by the conveyor. in order to prevent any vaporized particles which might condense or, agglomerate on the inside or the outside of the side walls 21 and 28 from forming drops which might fall off the upper edges of the inlet 28 or the outlet 88, each side wall is provided with a plurality of inclined gutters. Thus the side wall 21 is provided with gutters 8i and 82, and the other side wall 28 is provided with gutters 68 and 84 which as may be seen from Figure 3 extend to the end walls 28 and 24 of the inner chamber 22.

In order to transport articles through the apparatus there is provided a conveyor mounted upon 'tween the front wall I5 and back wall I1 of a pair of transversely extending support members or beams 85 and 88 mounted adjacent the back wall 28 and the front wall 24 respectively of the inner chamber 22. The members 85 and 88 may extend through the inlets and outlets to the exterior of the cabinet II. A plurality of shafts 81, 88, 88, 'II and 12 are suitably supported between the members 85 and 88. The shaft 81 is provided with a pluralityof sprockets 18, 14, and 15 which cooperate with a plurality of conveyor chains 18, 11, and 18 which operate on sprockets 18, 8i, and 82 mounted upon the shaft 88. The

shaft 88 is also provided with a plurality of sprockets 88, 84, and 85 upon which are mounted conveyor chains 88, 81, and 88 which travel over sprockets 88, 8|, and 82 mounted on shaft 88. The conveyor chains 88, 81, and 88 therefore are spaced to one side of the conveyor chains 18, 11, and 18 so that diiferent portions of the surfaces of objects moved into the apparatus by the conveyor chain will rest upon different supporting points as the spraying of the articles progresses. The shaft 88 is provided with additional sprockets 88, 84, and 85 upon which spray conveyor chains 88, 81, and 88 operate so that when the articles which are mounted upon the conveyor chains 88, 81, and .88 are transferred to the conveyor chains 88, 81, and 88, there is again brought about a change of the point of contact between the articles and support members comprising aportion of the conveyor chains. The shaft 1| is provided with a plurality of sprockets I88 to I85 upon which the chains 88, 81, and 88 and I88, I81, and I88 operate. The chains I88, I81, and I88 engage sprockets B88, III, and H2 upon shaft 12 which is driven by a pulley II8 having thereon a rangement from an electric motor H8. Each of the chains of the conveyor is preferably formed as shown in Figure 6 where the chain 89 at regular intervals is provided with pointed support members 90 for engaging the bottom side of objects to be coated such as a sheet of material In order to heat the material to be applied to the articles to be coated, the lower receptacle portion of the inner chamber 22 is provided with a plurality of electric heaters I2I, I22, I23, and I24 associated with the bottom portions 31 and 38 and the side portions 39 and M respectively. Each of the heaters I2I to I24 preferably is formed of a, plurality of individual strip heaters mounted so as to comprise an electrical heating unit readily removably from support members. To support the various electrical heating units, guide channels I25 to I3l inclusive are provided adjacent the bottom and side portions of the receptacle part of the inner chamber 22. In order that access may be had to the heater units, the bottom 33 of the outer cabinet may be provided with suitable openings I32 and I33; and of course side panel portions ofthe walls of the outer cabinet H such as the portions I34, I35, and I35 may be arranged so as to be readily removable. Preferably the two bottom heaters I2I and 522 and one half of each of the side heaters 523 and E24 are connected so as to be controlled by a single thermostat. The upper portions of the heaters I23 and I24 may be connected to a manually controlled switch for heating the material during a starting period or when the receptacle portion of the inner chamber 22 is loaded substantially to its capacity. Subsequently during the operation of the apparatus, particularly when a lesser quantity is in the receptacle, the thermostatically controlled heaters provide adequate heat for the material.

To apply the material to articles carried by the conveyor such as a sheet of material II9 two spray guns' I37 and I38 are mounted adjacent the top of the chamber 22, and two spray guns I39 and I49 are positioned in the receptacle portion of the inner chamber 22 just above the level of the maximum load of material to be heated. Each of the spray guns I31 to I40 is provided with a material conduit III to I44 respectively and with an air conduit I45 to I48 respectively. Each of the spray guns I31 to I40 is also provided with suitable drain pipes II to I54 respectively so that when it is desired to stop the apparatus the liquid heated material may be permitted to drain from the nozzle portion of each of the guns so that the material will not solidify therein and prevent ready resumption of the operation of the apparatus. The heated liquid material is supplied to the spray guns by a gear pump I49 driven by a belt and pulley arrangement from an electrical motor I55 mounted on the shelf "ion the outside of the cabinet II. When it is desired to close down the operation of the apparatus for any appreciable time, air must be supplied to the gear pump I49 by a valve I56 so that the liquid material may drain from the pump and also from the various conduits leading to the various guns. A valve IE1 is provided on the exterior of the cabinet II for drainmg 212518 receptacle portion of the inner. cham- Air under suitable pressure is supplied to an air cleaning or dehydrating device I58 which preferably is mounted on the front wall II of the cabinet I I so that the device is readily accessible for cleaning and for replacing the elements contained therein. This air cleaning or air conditioning device preferably is of the type disclosed in my copending application, Serial Number 489,211, filed May 31, 1943, although it is to be understood that other suitable types of devices may be employed. The outlet from the air condtloning device I 58 extends into the cabinet II where it joins a conduit I59 mounted in folded fashion on the lower portion of the wall 28, as may be seen in Figures 2 and 4, so that the air passing therethrough will be at a temperature in the proximity of the temperature of the heated material supplied to the spray guns. By supplying heated air to the spray guns the atomized particles of the coating material are enveloped in an atmosphere having a temperature such that the particles have a proper consistency so as to reach the surface of the articles to form a continuous coherent and adherent protective coating.

In operation the thermostatically controlled heater units adjacent the receptacle portion of the inner chamber 22 operates to heat thematerial I60 contained therein. When the material has been brought to the desired temperature so as to be of the proper'fiuid consistency, the motors H8 and IE5 are energized so as to bring about operation of the conveyor and the gear pump I49. The gear pump which is provided with an inlet extending toward the bottom of the receptacle portion of the inner chamber 22 supplies fluid material under pressure to each of the spray guns I31 to Iflt. Air from a suitable source is supplied through the air cleaning device I53 to the conduit I59 where the air is heated and then supplied to the various spray guns. The spray guns therefore atomize and project thecoating -which are in contact with the supports 90 of the conveyor chain 80 and also those portions which might be masked to some degree by the conveyor.

chains. The exhaust fan 58 removes from the chamber 22 all those particles ofatomized material which maybe suspended above the plate II9 particularly in the proximity of the inlet 29 and the outlet 33. Such suspended particles of material if permitted to pass beyond the inlet or outlet and come in contact with the plates II9, would not be at the proper temperature and would impair the finish desired. The exhaust fan 58 therefore draws the particles away from the.

inlet and outlet together with a certain amount of air from the hoods 32 and 35 up through the passages 54 and 55 into the stack 66.

The blower fan 49 circulates and recirculates air around a greater portion 'of the walls of the inner chamber 22 so that the chamber in its entirety has a predetermined operatingtempera ture so that temperature gradients within the chamber are minimized. The minimizing of temperature gradients within the chamber 22 is productive of a better protective coat upon the articles to be coated as there is greater assurance that the particles impinging upon the articles are at the proper temperature to produce the desired cohesion and adhesion with one another and with the surface 01 the article. By regulating the valve or damper 52 the operating temperature of the chamber 22 may be modified as desired since the thermostat which controls the strip heater elements is arranged to be primarily responsive to the temperature required for maintaining the material I60 at the desired fluid consistency, and the ambient temperature of the sheets H9 entering the apparatus may be such as to vary the temperature within the chamber 22 which therefore could be compensated for by the control valve 52.

While for the purposes of explanation a single embodiment of the invention has been disclosed, it is to be understood that it is not to be, limited thereby since obviously numerous variations may be made in the instrumentalities employed and in their arrangements without departing from the spirit and. scope of the invention as defined in the appended claims.

This invention is hereby claimed as follows:

1. A continuously operating spray coating inachine comprising a heat insulated cabinet having an inlet and an outlet for objects to be coated, a conveyor ior moving objects through said cabinet, an inner chamber mounted within said cabinet, said chamber having an inlet and an outlet for objects to be treated therein, means for electrically heating the lower portion of said chamber, and means including a fan for circulating and recirculating air around said chamber to minimize temperature differentials therein.

.2. A continuously operating coating machine comprising a heat insulated cabinet having an inlet and an outlet for objects to be coated, a conveyor for moving objects in and out of said cabinet, an inner chamber mounted within said cabinet, means for withdrawing air from the v upper. part of said chamber and from said inlet and outlet alongtwo of the outer sides of said chamber to the exterior of said cabinet, means for heating the lower portion of said chamber, and means for circulating and recirculating air around the bottom, two sides and top of said chamber.

3. A spray coating machine comprising a heat insulated cabinet having an inlet and an outlet for objects to be passed therethrough, a metal inner chamber mounted within said cabinet and spacedfrom the inner walls'thereof, said inner chamber having an inlet and an outlet, for objects to be passed therethrough and to be treated therein, means mounted within said inner chamber for coating the surfaces of objects passing therethrough, means for heating the lower portion of said chamber toheat material therein to be applied to the objects passing through said machine, and means for circulating and recirculating air about said inner'chamber to minimize temperature differential therein. 4. A spray coating machine comprising a heat insulated cabinet having an inlet and an outlet for objects to be passed therethrough, a metal innerchamber mounted within said cabinet and spaced from the inner walls thereof, said innerpassing objects therethrough, a metal inner chamber having an inlet and an outlet for objects to be passed therethrough and to be treated therein, a conveyor for passing objects through said machine, spray means mounted within said inner chamber for simultaneously coating the top and bottom of objects passing therethrough,

means for heating the lower portion of said chamber to heat material therein to be supplied to said spraying means, and means including a chamber mounted within and in spaced relation to said cabinet, the lower portion of said chamber serving as a receptacle for material-to be applied to objects passing through said chamber, said chamber having an inlet and an outlet for said objects, means for electrically heating the receptacle portionoif said chamber, said means being located adjacent the exterior sides and bottom of said chamber, a plurality of spraying devices located within said chamber for applying heated material to said objects, and means for circulating and recirculating air around, said chamber and said electrical heating means to minimize temperature difierentials within said chamber. a

b". The combination comprising a heat insulated cabinet, 2, metal inner chamber mounted. within and in spaced relation to said cabinet, said cabinet and said chamber each having an inlet and an outlet for objects to be passed therethrough, means for conveying objects through said chamber and said cabinet, the lower portion of said chamber serving as a receptacle for material to be applied to said objects, means for electrically heating the receptacle portion 01 said chamber, said means being located adjacent the exterior sides and bottom of said chamber, a plurality of spraying devices located within said chamber for applying said heated material to said objects, means for supplying to said spraying devices an aeriiorm substance under pressure including a conduit positioned adjacent the lower receptacle portion of said chamber whereby to heat said aeriform substance, and means for-producing forced circulation and recirculation of air around said chamber and said electrical heating means, to minimize temperature differentials within said chamber.

l. Acoating machine for spraying heated material on objects comprising a heat insulated cabinet having a middle inner chamber mounted therein in spaced relation thereto, inlets and outlets tor said cabinet and said chamber, a conveyor for passing objects through said inlets and said outlets, the lower portion or said chamber being arranged as a receptacle tor material to be applied to said objects, means associated with said lower portion 01 said chamber for electrically heating said material, a plurality of spray guns mounted within said chamber for completely coating said objects, a source 01! aeriiorm substance under pressure for said spray guns, means located adjacent the lower portion of said chamber for heating said aeriiorm substance'to be supplied to said spray guns, a suction ian for withdrawing the aeritorm substance from the upper part of said chamber, and means for producing forced circulation and -recirculation of air about said chamber and said heating means to minimize temperature gradients therein.

Acoating machine for spraying heated material to be heated and to be supplied to said.

spray guns, means associated with said lower portion of said chamber for electrically heating said riaterial, a-source of aeriiorm substance under pressure for said spray guns, means located adjacent the lower portion of said chamber for heating the aeriform substance to be supplied to said spray guns, a suction fan for withdrawing the aeriform substance from the upper portion of said chamber and from adjacent said inlet and said outlet, and means including a fan for producing the circulation and recirculation of air about said chamber and said heating means thereby to minimize temperature gradients within said chamber.

9. A coating machine comprising a heat insulated cabinet having an inner metal chamber mounted therein in spaced relation thereto, inlets and outlets for said cabinet and said chamber, conveyor means mounted between said inlets and said outlets, the lower portion of said chamber being arranged as a receptacle iormaterial to be heated for application to objects carried by said conveyor, a plurality of electric strip heating units mounted adjacent the bottom and sides of said lower portion of said chamber, meansforming an air conduit around the top, bottom,

and two sides of said chamber, means for producing forced circulation and recirculation of airthrough said conduit, means forming a conduit extending upwardly between two sides of and said outlets, the lower portion of said chamber being arranged as a receptacle for material to be heated for application to objects carried by said conveyor, a plurality of electric strip heatingunits mounted adjacentthe bottomand sides of I said lower portion of said'chamber, means forming an air conduit around the top, bottom and two sides of said chamber, means for producing forced circulation and recirculation of air through said conduit, means forming a conduit extending upwardly between two sides of said chamber and adjacent the top of said cabinet, said conduit being in communication with said inlets and said outlets, means for withdrawing air from the upper part of said chamber and from the proximities of said'inlets and said outlets through said conduit to the exterior of said cabinet, a plurality of air spraying guns mountedwithin said chamber, a source of air under pressure for said guns, means located adjacent the lower portion of said chamber for heating said air, and means for supplying heated material to 11. A continuously operating spray coating machine comprising a cabinet having an inlet and an outlet for objects to be coated, an inner chamber mounted within said cabinet, said chamber having an inlet and an outlet for objects to be coated therein, a conveyor for moving objects through said cabinet and said chamber, means for heating the lower portion of said chamber, and means including a fan for circulat-. ing and re-circulating air within said cabinet about said chamber to minimize temperature said chamber and adjacent the top of said cabinet,

said conduit being in communication with said inlets and said outlets, means for withdrawing air from the upper part of said chamber and 4 from the proxiinities of said inlets and said outlets through SflldCQIldllit to the exterior of said cabinet; a lurality, biainspraying guns mounted within said chamber, and means for supplying under pressure heated material and air to, said air spraying guns.

10; A coating machine comprising a' heat-insudifferentials therein.

12 A continuously operating coating machine comprising aheat insulated cabinet having an inlet and an outlet for objects to be coated, an inner chambermounte'd in spaced relation within said cabinet, said chamber having an inlet and an outlet for objects to be coated therein,

lated cabinetv having an inner metal chamber mounted therein in spaced relation thereto, inlets and outlets for said cabinet and said chamber, conveyor means mounted between said inlets a conveyor for moving objects in and out of said chamber and said cabinet, means for withdrawing air from said inlets and outlets along two of I the outer sides of said chamber to the exterior of said cabinet, means for heating the lower portion 01 said chamber, and means for circulating and re-circulatingv air around the remaining outer surfaces of said chamber.

- JENS A. PAASQHE. 

